Sensitive Image-Based Chromatin Binding Assays Using Inducible ERα To Rapidly Characterize Estrogenic Chemicals and Mixtures

Authors

Adam T Szafran
Maureen G Mancini
Fabio Stossi
Michael A Mancini

Publication Date

10-21-2022

Journal

iScience

DOI

10.1016/j.isci.2022.105200

PMID

36238893

PMCID

PMC9550643

PubMedCentral® Posted Date

9-23-2022

PubMedCentral® Full Text Version

Post-Print

Published Open-Access

yes

Keywords

Endocrinology, Biological sciences research methodologies

Abstract

The United States Environmental Protection Agency (EPA) has been pursuing new high throughput in vitro assays to characterize endocrine disrupting chemicals (EDCs) that interact with estrogen receptor signaling. We characterize two new PRL-HeLa cell models expressing either inducible C-terminal (iGFP-ER) or N-terminal (iER-GFP) tagged estrogen receptor-α (ERα) that allows direct visualization of chromatin binding. These models are an order of magnitude more sensitive, detecting 87 - 93% of very weak estrogens tested compared to only 27% by a previous PRL-HeLa variant and compares favorably to the 73% detected by an EPA-developed computational model using in vitro data. Importantly, the chromatin binding assays distinguished agonist- and antagonist-like phenotypes without activity specific assays. Finally, analysis of complex environmentally relevant chemical mixtures demonstrated how chromatin binding data can be used in risk assessment models to predict activity. These new assays should be a useful in vitro tool to screen for estrogenic activity.